a) Field of the Invention
The present invention relates to techniques for processing musical tone information, and more particularly to techniques for processing musical tone information of two kinds or more and reproducing it.
b) Description of the Related Art
As a standard specification for communications between electronic musical instruments, a musical instrument digital interface (MIDI) specification is known. Electronic musical instruments equipped with interfaces of the MIDI specification can communicate with each other by transferring MIDI data via a MIDI cable. For example, an electronic musical instrument transmits MIDI data of a musical performance made by a player, and another musical instrument receives it to reproduce it. As one electronic musical instrument is played, another electronic musical instrument can be played in real time.
In a communications network interconnecting a plurality of general computers, various types of data are transferred. For example, live musical tone data or other MIDI data can be transmitted from one computer, which once stored the data in its storage device such as a hard disk, via the communications network to another computer which stores the received data in its storage device. A general communications network is, however, configured to perform only general data communications, and is not configured to properly process MIDI data.
Specifically, although the MIDI specification allows the real time communications to be performed between electronic musical instruments, it is not suitable for long distance communications and communications via a number of nodes. The general communications network is essentially configured to provide services of long distance communications and multiple-node communications, but it does not take account of real time communications between electronic musical instruments.
Musical tone information includes MIDI data and audio data. The MIDI data conforms with the MIDI specification and includes a key-on event (e.g., key depression information), a key-off event (e.g., key release information). The audio data is data generated by a microphone for example. The microphone converts voices (including musical tones produced by musical equipments) into analog electric audio signals. The analog audio signals are converted into digital audio signals to obtain audio data. The audio data is stored, for example, in a compact disk, a digital audio tape, or the like.
A communications apparatus includes a transmitter and a receiver. The transmitter is desired to be able to transmit a mixture of MIDI data and audio data. The receiver is desired to be able to receive and reproduce both the MIDI data and audio data at the same time. It is possible to transfer only one of the MIDI data and audio data, but it is difficult to transfer a mixture of MIDI data and audio data.
Even if a mixture of MIDI data and audio data can be transferred, it is difficult to reproduce both the data synchronously. Although it is possible to start reproducing both the data at the same time, there is no means for synchronizing both the data after the start of reproduction.